A comprehensive review of nanosuspension loaded microneedles: fabrication methods, applications, and recent developments

Background Nanosuspension-loaded microneedles (MNs) are an emerging and advanced strategy used extensively to formulate lipophilic molecules by embedding them into a suitable polymer matrix for improved transdermal delivery. Area covered This review focuses on the nanosuspension/nanocrystal-loaded MN approach for improved delivery of hydrophobic molecules. This review discusses the different types of MNs that can be fabricated, such as dissolving, solid, coated, and hollow MNs and the criteria for the choice of the fabrication method. Expert opinion The drug loading of hydrophobic drugs can be significantly improved using this strategy. Recently, nanosuspension/nanocrystal-loaded MNs have been considered a well-recognized approach in drug delivery owing to their numerous advantages, including controlled drug release, non-invasiveness, and ability to be self-administered. The preparation of nanosuspension-loaded dissolving MNs has been widely carried out using knife-casting methods. In the present review, the various characterization methods, including the in vitro, ex vivo and in vivo techniques, are briefly discussed. Further, the review also describes the potential applications of nanosuspension-loaded MNs.